Background: Gustilo's grade IIIB classification includes a wide spectrum of injuries and is limited by high inter and intra observer error rates. Methods: A trauma score for grade IIIB open tibial fractures was devised to assess injury to three components; the covering tissues, musculotendinous units and bone with the severity scale in each category from one to five. Seven co-morbid conditions known to influence the prognosis were each given a score of two and summed up.Results : Ninety six consecutive Grade IIIB open injuries of tibia were prospectively evaluated. At 3-5 year follow up, of the 88 available, final score was less than five in 6 patients (Group I), between six and ten in 48 (Group II), eleven to fifteen in 29 (Group III) and above 16 in five (Group IV). All patients in Group IV and one in Group III with score of fifteen underwent amputation. There was a significant difference (p less than 0.001) between the three groups in the requirement for flap (16.7,75&100 percent), time for union (16.3,24.9 & 46.9), incidence of deep infection (0,22.9 & 60.7 percent), number of surgical procedures (1.2,3.1 & 6.3) and inpatient days (12.5,22.6 & 59.4). A score of greater than three in any one component required special skills in management and interfered with healing of other structures. Conclusion: The scoring system was easy to apply and had a high degree of interobservor aggreement rate. This comprehensive score reliably prognosticates both limb salvage and outcome measures in severe open injuries of tibia.

Keywords: Type IIIB open fracture; Scoring system.

How to cite this article:Rajasekaran S. Ganga hospital open injury severity score - A score to prognosticate limb salvage and outcome measures in Type IIIb open tibial fractures. Indian J Orthop 2005;39:4-13

Type IIIB open injuries of limbs are a major challenge in management being associated with a high incidence of non­unions[1],[2] , early and late infections[3],[4],[5] , a prolonged period of treatment[6] , a high number of secondary procedures[7] , poor functional outcome and the possibility of secondary amputations[8],[9] . It becomes necessary that there is a method available not only to predict salvage but also to provide guidelines in treatment and prognosticate the clinical outcome.

The most important factor determining the outcome is the severity of injury and the landmark classification of Gustilo and Anderson[10] is the most commonly used classification. Open injuries were divided into three types on the basis of the size of the wound and level of contamination. Type III injuries were later classified into Type IIIA, IIIB and IIIC according to the severity of the soft tissue injuries and the need for vascular reconstruction[11] . The classification was found to provide a rough guideline for the need for a flap cover and the incidence of infection. There are however many limitations to this classification which become obvious when a large number of open injuries are routinely managed[9],[12],[13],[14],[15],[16] and these problems are more specific to Type IIIB group of injuries as it includes a wide spectrum ranging from the easily manageable to the almost unsalvageable [Figure - 1]. The management and prognosis of these injuries are highly variable making this classification too generalized, all inclusive and therefore not specific or much use in prognostication. A Type IIIB injury involves injury to the covering tissues (skin and fascia), functional tissues (muscles, tendons and nerves), and skeleton (bones and joints) of the limb.

A true prognosticating score must evaluate each component of the limb separately and also collectively[15] , whereas Gustilo's classification is biased on the size and nature of the wound. The damage to the functional structures and severity of bone injury are not provided equal emphasis making it a poor predictor of outcome[15],[16],[17][Figure - 2]. The inter­observer agreement of Gustilo-Anderson classification system has also been found to be only moderate to poor, highly case dependent, varying with the experience of the surgeon and hence not an adequate basis for treatment decisions or for the comparison of published results[18],[19] . The sequence of treatment and decision of salvage or amputation cannot be done in isolation on the severity of injury to the limb. It is also dependent on the age of the patient, presence of systemic illnesses, injury to other systems, delay in presentation to the hospital, and the presence of risk factors like uncontrolled diabetes and cardio-respiratory illness[15],[16],[17] .Such factors must be given due consideration in a score which hopes to provide prognostication of the outcome.

The prediction for limb salvage has been addressed by the Mangled Extremity Severity Score[20] (MESS) and the Hannover Trauma Scale System[21] . MESS, while specifically addressing salvage does not provide guidelines for treatment or prognosticate outcome parameters in salvaged patients. The Hannover Trauma Scale System being very elaborate and cumbersome has not achieved popular and wide usage. The challenge is to evolve a system which is accurate enough to accomplish these aims but also simple in its application. We report here a score prospectively validated in a tertiary trauma center and found to have a high reliability for prediction of salvage and the outcome measures of inpatient days, rate of infection, requirement of a flap, number of secondary procedures and primary cost of treatment.

Materials and methods

The study was performed in a tertiary trauma referral center, which on an average managed 300 open injuries of limbs every year. Roughly half of them are Type IIIB injuries as the unit acts as a referral center for a population of over three million. An aggressive approach with immediate reconstruction is routinely performed whenever possible. Gustilo-Anderson's classification is routinely employed and it became apparent that it was inadequate in Type IIIB injuries to reliably provide guidelines regarding the type and extent of soft tissue reconstruction required, the management for bone union, the time to obtain bone union, the number of secondary procedures required, the duration of inpatient stay , and the approximate hospital cost. An 'Open Injury Severity Assessment Score' was developed in 1994 to prognosticate the above outcome parameters. After three clinical trials and suitable modifications, the score was derived to the present form and applied prospectively from February 1998, the results of which are presented here.

Principle of the score

The score allotted points from one to five according to the severity of injury to each of the three components of the limb: the Covering tissues (skin and fascia), Functional tissues (muscles, tendons and nerve units) and Skeleton (bones and joints). The presence of systemic factors which influenced the treatment and outcome, were allotted a score of two each and the final score arrived by adding the individual scores [Table - 1].

Score 'one' and 'two' for any tissue meant that no special secondary procedures would be required for the repair and healing of that particular structure and the ultimate outcome for the limb will not be poorly influenced by the injury of that structure. A score of 'three' meant that some special procedure will be required for healing of that tissue but a good functional outcome can be achieved with appropriate management. A score of 'four' or 'five' meant that the injury was of such severity, that it would involve multiple procedures for healing, would be a cause for prolonged hospital stay, would involve increased treatment costs, would negatively influence the healing of other components of the limb, and could ultimately lead to a poor functional outcome. Accurate assessment of the injury to each of the components was assessed at the end of debridement and scoring performed. As the criteria for scoring was very objective, unlike in Gustilo's classification, there was rarely a need for the change in the scores even when a relook procedure or serial debridement was necessary.

Score 1 : Wounds not present over the bone, which had adequate soft tissue bed and which could be sutured without tension after debridement were given a score of 'one'. These wounds, irrespective of dimension did not involve any loss of skin, did not require any additional plastic procedures, allowed primary appropriate treatment of skeletal injury and was not a deterrent for bony healing.

Score 2 : Wounds not present over the bone, but with primary skin loss or requiring excision of skin during debridement were given a score of 'two'. These wounds required skin grafting only which could often be done primarily or during the second look surgery. The choice of appropriate treatment for skeletal union was not negatively influenced by the nature of the wound.

Score 3: Wounds situated over the bone and directly exposing the skeleton but without skin loss either by injury or during debridement and which could be sutured primarily or secondarily without the need for a flap procedure were given a score of 'three'. The choice of bony stabilization had to be frequently modified as plate osteosynthesis was usually unsuitable due to a lack of soft tissue envelope. Careful follow up to monitor wound dehiscence which will then require a flap cover was necessary.

Score 4 : Wounds with primary skin loss and exposing bone or which require extensive debridement of the skin due to friction burns or degloving were given a score of 'four'. These demanded specialized plastic surgical skills and the performance of soft tissue cover at the earliest possible was mandatory for good outcome. Delay of soft tissue reconstruction in these injuries often leads to increased infection, a high rate of non-union, a need for prolonged antibiotic therapy and an increased number of secondary procedures.

Score 5 : Wounds involving skin loss over the entire circumference of the limb was given a score of 'five'. These wounds were often present around the joints where extensive degloving was frequent which lead to exposure of wide area of metaphyseal bone and joints. They often posed a challenge in soft tissue reconstruction and a period of a few weeks to months was lost before soft tissue reconstruction was complete and bone reconstruction could be started. Bony reconstruction was often dictated by the soft tissue reconstruction and a prolonged period of treatment was not uncommon.

Functional tissues: musculo-tendinous and nerve units

The damage to the musculo-tendinous units and neural structures was assessed according to the extent of damage, whether the damage could be repaired without functional loss and whether the injury involved either a single unit or an entire compartment [Figure - 4]

Score 1 : Exposure of musculo-tendinous units of any dimension without direct damage was given a score of 'one'. In this group, the tendons although exposed would have an intact tendon sheath which allowed primary or secondary skin grafting. There was no loss of functional units, no requirement of flaps and no functional loss.

Score 2 : A direct injury to the musculo-tendinous unit with loss of integrity but which could be primarily repaired with no loss of function was given a score of 'two'. Although there was no ultimate loss in function, rehabilitation procedures have to be delayed to allow healing of the repair of the muscle or tendon. Nerve injuries which can be primarily sutured leading to good motor recovery come under this category.

Score 3 : Crush injuries requiring debridement of an entire muscle or other types of irreparable injury to one or more muscles in a compartment was given a score of 'three'. These injuries required specific primary procedures to make good the functional loss and often involved tendon transfer procedures prolonging recovery. Crush injury of a major nerve with or without segmental loss was also given a score of four. These required complex surgical procedures like cable grafting or secondary tendon transfer procedures and a prolonged rehabilitation period.

Score 4 : Extensive damage of one entire compartment was given a score of 'four'.

Score 5 : Loss of two or more compartments was given a score of 'five'. Injuries with score four and five were always associated with extensive exposure and hypovascularity of the bones making overall treatment difficult and challenging. Crush injury of more than one major nerve with or without segmental loss was also given a score of five.

Skeletal structures: bone and joints:

The personality of the fracture, the vascularity of the bones, involvement of the joint and the extent of bone loss determined the score [Figure - 5].

Score 1 : Transverse or oblique fractures with minimal periosteal stripping are given a score of 'one'. These are highly amenable for all modes of bony stabilization including primary fixation with interlocking nails. There is no bone loss or hypo-vascular fragments which require excision or secondary bone grafting.

Score 2 : Presence of unicortical comminution, presence of a large butterfly fragment involving more than 50% of the circumference or segmental fractures without bone loss was given a score of 'two'. The soft tissue attachment to the butterfly fragment determined the salvageability of the fragment and experience was required for correct judgment to retain these fragments. The union time was usually delayed and the need for bone grafting is higher.

Score 3 : Extensive periarticular comminution with joint disorganization was given a score of 'three'. These injuries had a poor soft tissue envelope, the break down of which often lead to dificulties in reconstruction. Although union was achieved without dif ficulty a combination of periarticular skeletal and soft tissue loss led to an increased need for soft tissue reconstruction and bone grafting procedures, higher infection rates, joint stiffness/ deformities and a poor functional outcome.

Score 4 : Circumferential comminution of bone with or without bone loss of less than four cm was given a score of 'four'. Secondary procedures to attain bony union are a must. Apart from bone grafting techniques, bone transport was frequently necessary leading to prolonged treatment time and delay in return to normalcy.

Score 5 : Comminuted or segmental fractures with primary or secondary loss of bone greater than four centimeters were given of score of 'five'. Bone transport and other complex procedures were required and reconstruction was frequently complicated by presence of associated severe soft tissue injury.

Co-morbid Factors

Factors which negatively influence the management and outcome in open injuries, were each given a score of two [Table - 1]. Delayed presentation leading to a delay in debridement is associated with the need for serial debride­ments, increased secondary loss of tissues, a high incidence of infection, and the number of secondary procedures that are required. Uncontrolled diabetes mellitus, an age above 65 years, presence of cardio-respiratory diseases, polytrauma involving chest and abdominal injuries with an injury severity score of greater than 25, fat embolism, compartment syndrome also make major reconstructive procedures risky and interfere with the sequence of reconstructive procedures. Presence of each of these factors was each given a score of two and the final score computed.

Inter-observer reliability

The inter-observer reliability was calculated by 10 surgeons assessing 12 consecutive patients with Type IIIB open injury of the tibia. The observers comprised of three consultants, two trauma fellows, two registrars and three senior house officers who were in the second and third year of orthopaedic training. The level of inter-observer agreement for the score of each injury was determined according to the largest number of observers who chose a single specific score. The average agreement in total score by kappa analysis was very high at 98.4 per cent (96.7 to 99.7 per cent). The average agreement for grouping was 97.9 per cent (86.9 to 99.7 per cent).

Patient details

During the period of study of eighteen months starting from February 1998, a total of 268 open injuries were treated. Of them, 96 consecutive patients with Type IIIB injuries of tibia formed the study group. Two patients who died during their inpatient stay, one patient who died after discharge but before the treatment was complete, three patients who were referred to other centers for follow-up treatment and two patients who were lost to follow up were excluded from the study. The remaining 88 open Type IIIB injuries of tibia were prospectively followed till completion of treatment.

All patients were treated by a standard protocol with intravenous antibiotics (1.5gms of cefuroxime) and anti­tetanus prophylaxis on arrival. Debridement was performed by experienced surgeons at consultant level as soon as the patient' s condition would allow and was on an aggressive basis ensuring that no devitalized structure was left behind. Appropriate primary skeletal stabilization was done and a soft tissue cover was done at the earliest possible, if primary soft tissue cover could not be achieved. The method of bony stabilization was chosen depending upon the fracture configuration. Hybrid fixation was used for five metaphyseal fractures of tibia, interlocking nailing as an isolated procedure in 36, external fixators as an initial or definitive procedure in 28 patients and limb reconstruction system in 19 patients.

Results

The average age of the 88 patients was 36.3 years (16 to 73 years). 83 were males and five females. The mode of injury was road traffic accident in 72 patients, industrial accident in 10, fall from a height in three and farmyard injuries in three. 54 patients had associated co-morbid conditions. Forty patients had a single co-morbid condition, 12 patients had two and two had three co-morbid conditions. Two patients were older than 65 years, 24 patients had another injury to the same limb, three patients had fat embolism, four injuries were grossly contaminated with sewage or farmyard injuries, five patients had associated debilitating diseases, twelve patients had associated systemic injuries, and the injury debridement interval was more than 12 hours in 20 patients. All patients were followed up till the completion of the treatment and were monitored carefully for the following parameters. The distribution of the score for the 88 patients is given in [Table 2]. The final score was less than five in six patients (Group I), between six and ten in 48 (Group II), between 11 and 15 in 29 (Group III) and 16 or above in five patients (Group IV).

In the assessment of the injuries to the covering tissues, a score of one was noted in two injuries, a score of two in 7, a score of three in 15 injuries, a score of four in 60 and a score of five in four cases. In the score of functional units, 56 patients had a score of one, three patients a score of two, 16 patients a score of three, eight patients a score of four, five patients a score of five. In the injury to the bone and joints, 14 patients had a score of one; 32 patients a score of two, ten patients a score of three, 12 patients a score of four and 20 a score of five.

Limb salvage

All the five patients in Group IV, one of the five patients with score 15 underwent amputation. Similarly all five injuries with score of five in functional units or a score of five in any of two components underwent amputation. Five amputations were done within seventy-two hours, four of them primarily and one at first look debridement.

One patient in Group IV managed by latissimus dorsi free flap underwent secondary amputation because of uncontrolled infection and difficulties in bone reconstruction. The outcome in the first three groups showed a significant difference in all criteria measured [Figure - 6].

In-patient days

The average number of inpatient days for Group I was 12.5 days compared to 23.9 in Group II and 61 in Group III (P<0.0001 between each group). The patients in Group I had only one admission compared to 2.1 admissions for Group II and 3.2 for Group III and 1.2 for Group IV. The inpatient days for Group IV (31.2 days) were lesser than Group III as patients underwent amputation and required lesser secondary procedures or readmission.

Rate of infection

32 of the 88 patients had infection and the incidence varied in the three groups. None of the patients in Group I had infection compared to 11 of 48 (22.9%) in Group II and 17 of 28 salvaged limbs (60.7%) in Group III (p <0.001 between each group). The other four infections were stump infections in Group IV. Three of the infections in Group II and two of the infections in Group III settled by conservative methods whereas others required sur gical intervention for complete cure

Types of skin cover procedure

Only one out of six in Group I required a skin cover procedure compared to 36 of 48 (75%) in Group II and all of 28 salvaged limbs in Group III (P<0.0001). Five of the procedures in Group II were only skin graft procedure while all in Group III required flaps. Of the flap procedures done, eight of 31 in Group II and five of 28 in Group III were free flaps.

Number of surgical procedures

The average number of surgical procedures required for Group I was 1.2 compared to 3.1 in Group II and 6.3 in Group III (P<0.0001). All procedures in Group I and 86% of the procedures in Group II were done during the primary admission whereas 57% of the procedures in Group III were done in subsequent admissions.

Primary cost of treatment

The average primary cost of treatment (in thousands of rupees) for Group I was 52.8 compared to 123.7 in Group II and 306.5 in Group III (P<0.0001). These costs included only primary cost of treatment and the secondary loss of income and earning was not calculated. Apart from the total score, it was interesting to note that the severity score for individual structures also had a good correlation to the relevant parameters studied.

Score for covering structures

The score for the skin and covering structures correlated well with the nature of skin cover required, requirement of amputation, the total days of inpatient stay, rate of infection, number of procedures required and cost. While only four of 24 patients (16.7%) with a score of three or below required flaps, 56 of 58 patients (96.6%) whose limb survived with score of four and five required flap cover. All the three flaps done for patients with a score of three or below were local flaps, 37 out of 56 flaps in patients with score four and five were free flaps (p<0.001).

Score for functional tissues

The score for musculo-tendinous units had good correlation with the type of soft tissue cover required, the need for amputation, number of procedures and cost. While only 35 of 56 patients with score 'one' required a flap, all the three patients with score 'two' and 15 out of 17 in score 'three' required a flap. Of the eight injuries with score of 'four', one was amputated and the remaining seven required flaps, four being free flaps. While none of the patients with score 'three or below' required amputation, one of eight patients with score 'four ' and all five injuries with score 'five' underwent amputation.

Score for skeletal structures

The average time for achieving bone union in weeks was 18.9 for score 'one', 29.9 for score 'two', 29.1 for core 'three', 30.8 for score 'four ' and 51.9 for score 'five'. The time for union for injuries with scores 'two' and 'three' were the same as there was no bone loss in both the groups. The score not only correlated well with the time of union but also correlated with the mode of treatment and the need for bone grafting. Thirty-four of the 46 patients with score 'one or two' could be treated primarily with inter locking nailing, whereas this was possible in six of 12 patients in score 'four' and four of 20 in score 'five'. Similarly bone grafting was required in none of patients with score 'one', compared to eight of 32 patients with score 'two' and one of 10 patients with score 'three'. While none of the patients with a score of 'three or below' required bone transport, four of 12 patients with score 'four' and all of 14 salvaged limbs with score 'five' required limb reconstruction apparatus with bone transport (p < 0.001). Injuries with score 'one' required no secondary bony procedures to achieve union compared to eight of 32 (25%) patients with score 'two', two of 20 (20%) patients with score 'three', all of 12 patients with score 'four ' and all of 14 salvaged (100%) patients with score 'five'.

Discussion

Major advances have been achieved in the last couple of decades in the management of open injuries of limbs, which has helped us to achieve restoration of function to the patients. Improvements in intensive care management of the patients with polytrauma, the availability of powerful antibiotics, aggressive management by radical debridement, immediate bony stabilization and early soft tissue cover have largely improved the rate of salvage of limbs and improved the functional outcome. However these injuries continue to remain as a major challenge in management with a high potential for loss of limb or life and a poor functional outcome even after adequate treatment[22],[23],[24].

Although multi-factorial, the outcome in Type IIIB injuries of limbs depend mainly on the severity of the injury to the various components of the limb[12],[13],[15],[25]. Gustilo and Anderson made a land mark contribution when they described in 1976 a classification for open fractures that was based on the size of the wound[10] . Type III open fractures, which had extensive soft tissue damage and crushing was shown to have worse prognosis due to a higher rate of infection, nonunion, and secondary amputations compared to type I and II. In 1984, Gustilo et al reported a sub-classification of Type III open fractures[11] . Type IIIA injuries had adequate coverage of soft tissue of a fractured bone despite flaps or extensive laceration of the soft tissue; Type IIIB injuries had extensive soft tissue injury with periosteal stripping and exposure of bone, and usually with massive contamination; and Type IIIC injuries had an open fracture with an arterial injury requiring repair for salvage of the limb. This classification has since then gained wide popularity and is widely used.

While Type IIIA and IIIC injuries do not pose any problems in evaluation, Type IIIB injuries include a wide spectrum of injuries, from the easily manageable to the barely salvageable making this classification inefficient in providing guidelines in management or prognostication. There are many problems specific to Type IIIB injuries which become obvious when a large number of such injuries are managed[9],[12],[13],[14],[15],[16] .

Gustilo's classification is biased on the size of the wound rather than the extent of injury to all components of the limb[9],[14],[15],[26] . The energy of injury is dissipated to all the structures of the limb and the severity of injury to each component may have little relevance to the dimensions of the external wound [12],[26]. A high velocity gun shot wound generates approximately 2000 foot-pounds of energy, while an injury sustained by a pedestrian hit by a motor vehicle can result in liberation of at least 1,00,000 footpounds of energy[27] . The limb absorbs the energy on contact and then releases it in an explosion that comminutes bone and creates a soft tissue shock wave which strips the periosteum, tears apart the skin causing a momentary vacuum that sucks adjacent foreign material into the depths of the limb. The amount of deep tissue contamination and devitalisation does not correlate to the obvious dimensions of the wound [8],[12],[15],[20]. Although categorized as Type IIIB injury, an open injury with a severe involvement of one component has a different treatment protocol and a functional outcome compared to an injury with severe involvement of more than one component[28] . A system to assess the severity of the injury of each component individually and the limb in total is clearly necessary[14],[15],[16],[20],[28] .

Gustilo's grading can change with debridement and again if the wound requires redebridement[29],[30] . This undermines the value of the classification as an initial guide to treatment[31],[32] . Although the classification was initially proposed as an assessment before debridement, at a later date, Gustilo agreed that the classification done at the time of initial presentation is often inaccurate and the final grading must be done only after the debridement has enabled the surgeon to determine what kind of soft tissue reconstruction is needed[29]. He also agreed that the grading may need revision after each debridement[29], but this message is not well spread among the surgeons at large who come into contact with these severe injuries occasionally[30].

The classification into Type III A, B and C has a high degree of subjectiveness on the part of the evaluating surgeon. Two major reliability tests have been done on the Gustilo's method of classification, both of which have reported a low inter-observer agreement[18],[19] . The average agreement among all observers was only 60% and it was found to vary with the experience of the surgeon and also the type of the fracture. Of importance, some injuries were classified by a significant number of surgeons to three different grades as opposed to only two. In one particular case 42% opted for a classification of Type I, 25% for type II, and 25% for Type IIIA. Even considering the broader categories of severe (IIIA, IIIB, IIIC) and less severe (I, II) there was still a significant interobserver variation. They noted that less severe injuries may be given the same classification as more severe ones. It was concluded that this classification system was not an adequate basis for treatment decisions or for the comparison of published results and a more detailed, accurate, and objective criteria for the classification of open fractures should be pursued [8],[19],[30]. They did not however propose an alternative.

It is obvious that there is a need for a more accurate assessment system for Type IIIB injuries which have numerous problems in the present form. The definition of Type IIIB injury and its sub-classifications has been so frequently modified that even the specific definition of each type is no longer universal. Further, the existing criteria of classification is too subjective and permits too much of overlap between types and creates a non- mutually exclusive classification system. In pathology such as Type IIIB injury with a high degree of medicolegal significance, a scoring system, which evaluates Type IIIB injuries more objectively to provide accurate prognostication of outcome measures, is desirable. The proposed score was found to be easily applicable and with an average interobserver agreement rate of 98.4 per cent for the total score and 97.9 per cent for the group allocation. The criteria for assessment are well defined with little scope for subjective interpretation. The major advantage over the Gustilo's system is that each component of the limb is assessed separately, then collectively and the associated factors that influence the treatment and outcome are also given adequate importance. This allows a wholesome assessment of the limb and the plan of management in relation to the age and general condition of the patient. The proposed score also allows identification of the potential area of dif faculty in management. By assessing each system separately and scoring them individually, it was possible to assess the needs of each system and also judge the influence that it would exert on the healing of the other systems[28]. A score of less than two in any system meant that particular component was not very severely damaged, would require no special skills in management, would not be a source of poor result and would not interfere negatively on the management or healing of the other systems. There was a significant decrease in need for flaps and plastic surgical procedures in patients with a score of less than 'three' (4 of 24) compared to patients with a score above three (56 of 58 salvaged limbs) in covering tissues. The time for bony union was also significantly increased when the bone score was more than three. The need for specialized plastic surgical procedure, the number of inpatient admission days, the number of secondary procedures was all significantly more when the score was less than three or more for the musculo tendinous units. A score of four and five indicated an injury to a component of such severity, that it would demand specialized skills in reconstruction, involve multiple secondary procedures, would be a source of poor functional outcome and the injury would interfere with the appropriate management of the other components. An injured limb, which gets a score of more than three in two or more components, would be a challenge in salvage and functional outcome might be compromised. Extensive bone loss, severe disorganization of the joint, loss of entire compartments or the presence of multiple co morbid factors would be good example for the situation. The decision to salvage and the treatment of these severe injuries must be at specialized centers where highly qualified and experienced teams of anaesthetic, orthopaedic and plastic surgeons are available. The score gives an early indication for the need for specialized treatment so that early referrals to appropriate centers can be made. This would improve salvage and also the functional outcome. An injury with a score of five in more than one component led to amputation. While the scores of individual components of the limb provide a reliable method of evaluation of the extent of damage of that tissue and provided a guideline for treatment, the total score gave a good indication of the outcome measures analyzed. Patients were divided into four groups depending on the final score.

Group I included patients with a score of five or less, while Group II included patients with a score between six and ten, Group III included patients with a score of 11 to 15 and Group IV a score of more than 15. Significant difference in outcome in all the parameters evaluated was observed between each groups in all the important parameters considered. The requirement of flap in Group I was only one of six (16.7%) compared to 31 of 48 (64.58%) in Group II and all of 28 salvaged limbs (100%) in Group III (p<0.0001). A more accurate assessment for the need for flap can be obtained on day one by the score for covering tissues. While only four patients out of 24 required a flap when the score was three and below, 56 of 58 salvaged limbs required a flap when the score exceeded three for covering tissues. This indicated that whenever the score was more than three the need for plastic team was important and their involvement from day one was crucial for good results. If such facility is not available, then transfer of the patient was mandatory. Similarly the average bone union time also precipitously increased form 16.3 weeks for a bone score of 'one' to 46.9 weeks for a bone score of 'five'. It is important that the possibility of limb salvage is accurately assessed at beginning of treatment itself[32] . The proposed score was found to predict the need for amputation with a high degree of accuracy. All patients in Group IV underwent amputation. The only other patient who required amputation had a high score of fifteen. All patients with a score below fifteen were salvaged. The need for amputation was also indicated by high scores in musculoskeletal and soft tissue injury. All five patients with a score of five in musculoskeletal injury had an amputation and the other patient had a score of four. All had a bone score of five. Injuries with a score of 15 or more and with score of five in any of the three components would pose challenges in management and require a skilled team to judge the management and salvage options.

MESS has been found to accurately predict the need for amputation in trauma victims[20] . The score is based on skeletal/ soft tissue damage, limb ischaemia, presence of shock and age. In both retrospective and prospective trials a score greater or equal to seven was found to accurately assess the need for amputation. The score however does not predict the outcome in salvaged patients. The present score is superior to the MESS as it not only predicts requirement of amputation but can also identify the source of problems in management. As it assesses the injury to all components of the limb separately it also predicts the outcome measures in any type IIIB injury of tibia. The only other system which evaluates limb injuries on basis of points is the Hannover Trauma Scale system[21].

This is an extension of the evaluation of the soft tissue injury scale proposed by Tscherne[33] . The score is extensive, allows evaluation of both closed and open fractures but is less widely used because of being exhaustive, too elaborate, and cumbersome. The assessment of fracture pattern is based on AO classification and additional score is provided for butterfly fragment or presence of bone loss of greater than two centimeters. The length of the butterfly fragments and not the width or circumference of the bone, which is more crucial, is given importance. Soft tissue injury is evaluated on three criteria of nature and extent of injury to skin, presence and nature of skin defect and extent of injury to soft tissues. All the above are estimated as a percentage of the circumference of the limb and this may not be accurate in linear wounds and defects and also closed degloving with crushing of tissues.

The level of contamination is assessed by the number of foreign bodies present which is an inaccurate method of assessing contamination. Clinical assessment of bacteriological contamination is impossible at the time of initial debridement. The presence and duration of ischemia, injury to nerve and delay of treatment are the other factors assessed. The system is not widely used because of being too elaborate and the above mentioned difficulties.

The proposed score in comparison to other scores is simple yet comprehensive, measures all components of the limb, is easily applicable and has a high inter-observer agreement rate. By virtue of classifying the wide spectrum of Type IIIB injuries into well defined groups using a simple and objective criterion with a high inter-observer agreement rate, the score can also be used to compare the results of different treatment modalities from different centers.

Conclusion

The proposed score has the following advantages over the existing classifications and scoring systems:

This score acts as a predictable single scoring system for both limb salvage and also prognosticating outcome measures of requirement of flap procedure, number of inpatient days, union time, rate of infection, number of surgical procedures required and primary cost of treatment in the salvageable limbs.

The score is based on well-defined objective criteria and has an average inter-observer agreement rate of 98.4 per cent for the total score and 97.9 per cent for group allocation.

It evaluates the severity of injury to all components of the injured limbs separately and collectively and takes into account the importance of co-morbid factors which influence the treatment and outcome.

It can be used effectively to compare the results of different modalities of treatment and the results from different centers as the nature of injury to each component is assessed very objectively.